# std::basic_string<CharT,Traits,Allocator>::starts_with

From cppreference.com
< cpp‎ | string‎ | basic string

constexpr bool starts_with( std::basic_string_view<CharT,Traits> sv ) const noexcept; | (1) | (since C++20)
constexpr bool starts_with( CharT ch ) const noexcept; | (2) | (since C++20)
constexpr bool starts_with( const CharT* s ) const; | (3) | (since C++20)

Checks if the string begins with the given prefix. The prefix may be one of the following:

1) A string view `sv` (which may be a result of implicit conversion from another `std::basic_string`).
2) A single character ch.
3) A null-terminated character string s.

All three overloads effectively return std::basic_string_view<CharT, Traits>(data(), size()).starts_with(x), where `x` is the parameter.

### Parameters

sv | - | a string view which may be a result of implicit conversion from another `std::basic_string`
ch | - | a single character
s | - | a null-terminated character string

### Return value

true if the string begins with the provided prefix, false otherwise.

### Notes

Feature-test macro | Value | Std | Feature
--- | --- | --- | ---
`__cpp_lib_starts_ends_with` | `201711L` | (C++20) | String prefix and suffix checking: starts_with() and ends_with()

### Example

Run this code

    #include <cassert>
    #include <string>
    #include <string_view>

    int main()
    {
        using namespace std::literals;

        const auto str = "Hello, C++20!"s;

        assert
        (""
            && str.starts_with("He"sv)  // (1)
            && !str.starts_with("he"sv) // (1)
            && str.starts_with("He"s)   // (1) implicit conversion string to string_view
            && !str.starts_with("he"s)  // (1) implicit conversion string to string_view
            && str.starts_with('H')     // (2)
            && !str.starts_with('h')    // (2)
            && str.starts_with("He")    // (3)
            && !str.starts_with("he")   // (3)
        );
    }

### See also

ends_with (C++20) | checks if the string ends with the given suffix (public member function)
starts_with (C++20) | checks if the string view starts with the given prefix (public member function of `std::basic_string_view<CharT,Traits>`)
ends_with (C++20) | checks if the string view ends with the given suffix (public member function of `std::basic_string_view<CharT,Traits>`)
contains (C++23) | checks if the string contains the given substring or character (public member function)
contains (C++23) | checks if the string view contains the given substring or character (public member function of `std::basic_string_view<CharT,Traits>`)
compare | compares two strings (public member function)
substr | returns a substring (public member function)

Retrieved from "https://en.cppreference.com/mwiki/index.php?title=cpp/string/basic_string/starts_with&oldid=156934"